Clamping mechanism for lift trucks



April 27, 1965 E. G. BJORKLUND ETAL 3,180,572

CLAMPING MECHANISM FOR LIFT TRUCKS 4 Sheets-Sheet 1 Filed Dec. 21. 1961 INVENTORS: 66 0/ [my Law April 1965 E, s. BJORKLUND ETAL 3,180,672

CLAMPING MECHANISM FOR LIFT TRUCKS 4 Sheets-Sheet 2 Filed Dec. 21. 1961 INVE flmerfifi lor/elurzd, Lomdf/addo J11, fin,

NTOR5 April 1965 E. a. BJORKLUND ETAL 3,180,672

CLAMPING MECHANISM FOR LIFT TRUCKS Filed Dec. 21. 1961 4 SheetS Sheet-3 INVENTOR. EZflZerG fijarlzlzzzzd ZOW addock,

April 27, 1965 E. s. BJORKLUND' ETAL 3,180,672

CLAMPING MECHANISM FOR LIFT TRUCKS 4 Sheets-Sheet 4 Filed Dec. 21. 1961 mvsmons:

United States atent 3,186,672 CLAMPING MECHANiSll/l FQR LIFT TRUK Elmer G. Bjorklund and Louis A. Haddock, in, Battle Creek, Mich, assignors to Clark Equipment Company, a corporation of Michigan Filed Dec. 21, 1961, Ser, No. 160,983 4 Claims. Cl. w t-$8) The present invention relates to a rotatable clamping device adapted to be used as an elevatable attachment on the lifting mast of an industrial lift truck, and to be utilized for transporting and stacking cylindrical objects of widely varying diameters, such as paper rolls or the like, in either vertical or horizontal positions.

More specifically, the invention relates to a clamping mechanism of the character mentioned comprising a pair of clamping arms mounted on slides and movable towards one another by hydraulic actuating means for clamping engagement with loads of various diameters, one of the clamping arms being rigidly secured to a first arm carrier slide member, and the other of the clamping arms being pivotally mounted on a second arm carrier slide member and guided by cam and cam follower means, whereby as the two arms are moved toward one another, one arm will also be pivoted inwardly toward the other to supplement and thereby accelerate the clamping action effected by rectilinear movement of the respective slide members.

One object of the present invention is to provide a clamping mechanism of the foregoing type having two opposed clamping arms, one of which is pivotally mounted on a corresponding arm carrier slide member by hinge pin means, and to provide in conjunction therewith cam and cam follower guide means for continuously controlling the pivotal position of said one arm.

Another object is to provide such a clamping mechanism embodying an arm carrier slide having-an improved torque transfer member for transferring clamping forces from a pivotable clamping arm to a clamp base member, said transfer member comprising a torsion tube having a pair of mounting arms for hingedly supporting the pivotable clamping arm, and a pair of bearing plate members which carry bearing means thereon.

A further object of the invention is to provide a clamping mechanism as last aforementioned wherein each slide member carries two outwardly projecting parallel bearing plates, and each of said plates has a pair of spaced apart generally cylindrical bearings welded thereto and adapted for reciprocation in tubes which form elements of a clamp base structure.

The above and other objects will appear from the following detailed description of a preferred embodiment of the invention.

Now in order to acquaint those skilled in the art with the manner of utilizing and practicing our invention, we shall describe in conjunctionwith the accompanying drawings a preferred embodimentthereof.

In the drawings: 7

FIGURE 1 is a perspective view of a clamping mechanism constructed in accordance with the present invention and mounted on the lifting mast ofan industrial lift truck,

the clamping arms being shown in extended positions and a rotatable clamp base being shown intermediate its horizontal and vertical positions;

FlGURE-Z is an enlarged front elevational view showing the clamping mechanism rotated to its horizontal position, a front cover plate for the rotatable clamp base being removed to illustrate the interiorparts thereof;

FIGURE 3 is an exploded perspective view illustrating certain elements of the clamping mechanism, particularly the rotatable clamp base and two arm carrier slides which are adapted to be mounted in saidb'ase for reciprocation towards and away from one another, said view being substantially from the rear of the mechanism and showing the same rotated degrees from the position of FIG- URE 2; and p FIGURE 4 is a substantially enlarged perspective view showing the clamping arms in their approximate innermost positions with one arm pivoted inwardly toward the other.

FIGURES 1 and 4 show an industrial lift truck 20 having a lifting mast 22, the latter including an elevatable cross beam 24 (shown best in FIGURE 4) on which the clamping mechanism assembly is hung for movement upward and downwardly upon operation of the mast. The portion of the clamping mechanism assembly which is fixed with respect to the cross beam 24 includes a hanger plate 26 having attached thereto a pair of brackets 28 (one of which is shown) which hook over the upper edge of the beam 24 to hang the clamping mechanism thereon. If desired, the clamping assembly may also be bolted or otherwise further secured to the cross beam 24.

The fixed portion of the clamping mechanism assembly further includes a pair of double acting hydraulic cylinders 30 and 32 which serve to rotate a clamp base assembly 34 to permit loading, transporting, and stacking of paper rolls in either vertical or horizontal positions. The structure and operation of a rotating mechanism particularly suitable for use with the present invention is fully described in a co-pending application entitled Carriage Rotating Mechanism for Lift Trucks and the Like, filed February 5, 1962, by William A. Norlander, Serial No. 170,879, and assigned to the assignee of the present invention.

FIGURES 1 and 3 show arm carrier slide members 36 and 38 which are mounted in the base 34 for reciprocation towards and away from one another, the slide 36 being adapted toca'rry a pivotable clamping arm 40, and the slide 38 being adapted to carry arigid clamping arm 42.

The slide 36 (shown best in FIGURE 3) has a base comprising a torsion tube 44 which-has welded thereto a pair of spaced parallel'bearing plates 46 and 48 which are perpendicular to the tube 44 and extend outwardly therefrom toward the opposed slide 38. Welded to the plate 46 are a pair of generally cylindrical bearings 50 and 52 which are adapted to be enclosed by covers made of a suitable bearing material such as phenolic or nylon or the like, as shown at 53 and 54.

More specificall the bearing 50 comprises a generally it-shaped member formed from a relatively thick flat disc or cylindrical member by cutting a fiat-sided slot therein of a thickness approximately equal to the thickness of the bearing plate 46. The bearing 59 is assembled on the far inner end 59 of the plate 46 (the terms inner and .outer being used herein with reference to the over-all clamping mechanism assembly) with the bottom of the slot seated against the forward edge of the latter, and

the bearing is then welded in position, after which the bearing cover 53 is assembled thereover. The bearing 52 similarly comprises a relatively thick disc or cylindrical member which is provided with a flat-sided slot and is seated on the plate 46 near the outer end thereof and welded in position.

It will be noted that the inner bearing 5% is assembled on the plate 46 from the front thereof so that the slot in said member faces rearwardly, while the bearing member 52 is assembled in opposite fashion with the slot in said member facing forwardly. This is desirable since, under the forces developed during clamping operations, the bearing 59 will be urged rearwardly and the bearing 52 urged forwardly with respect to the bearing plate 46. The plate this provided with bearings 62 and 63 which ing cylinder 1%.

3,1 5 are substantially identical to the above-described bearings Ell and 52.

A pair of parallel support arms 64 and as are welded to the torsion tube .4 axially outwardly of the bearing plates 46 and 43, said arms being disposed approximately at the respective ends of the tube. The support arms 64 and as extend generally forwardly from the torsion tube 4 and are provided at their forward ends with pivot pin holes 67 and 68, whereby the clamping arm dd may be pivotally mounted thereon, as will be more fully described hereinafter.

A lug 70 is welded to the torsion tube 44 approximately midway between the bearing plates 46 and 48 and serves to anchor a hydraulically actuated piston (to be described later erein) to the slide 36 to permit reciprocation of the latter toward and away from the opposed slide member 33.

The slide member 38, provided to carry the rigid clamping arm 4-2, comprises a fiat base plate 72 which has welded thereto a pair of spaced parallel bearing plates 74 and 76, and also a lug 77 positioned intermediate the s erz hearing plates for permitting connection of the slide 38 i to a corresponding hydraulically actuated piston. Bearings 78 and 79 are welded to the plate 74, and bearings 8t and $1 are welded to the plate 76, the bearings 7% and 79 being spaced from one another and being assembled on the plate 74 from the rear and forward sides thereor", respectively, and the bearings 86 and 81 being similarly spaced and assembled on the plate 76 from the rear and forward sides thereof, respectively.

Each of the four bearings for the slide 38 comprises a generally "IE-shaped member substantially as described hereinabove with respect to the bearing 5% on the oppos ing slide 36. A pair of bearing covers are indicated at 32 and d3, it being understood that one cover member made of a suitable bearing material such as nylon or phenolic is supplied for each of the our bearings on each slide member. Holes $4 are provided in the base plate 72 to permit the clamping arm 42 to be rigidly bolted to the slide 38.

FIGURE 2 shows the assembled position of the various elements of FIGURE 3 together with the clamping arms 49 and 42. The clamp base assembly 34 includes a first pair of tubes 86 and 88 in which the bearings St) and 52.

on the bearing plate as, and the bearings 62 and 63 on the bearing plate 43, are slidably mounted, respectively. The tube 86 is provided with a longitudinal slot 9%) to accommodate the plate .6, and the tube 88 is similarly pro vided with a longitudinal slot 92 to accommodate the plate 48. It will now be seen that the slide 36 is carried by the clamp base assembly 34- for reciprocation toward and awayfrom the opposed slide 38, the four bearings on said slide 36 being slidably received Within the tubes as and 88, respectively.

In a similar manner, the slide 38 is carried by'the clamp base assembly 34 for reciprocation towards and away from the slide 36, the bearings 78 and 79 being received in a tubular member $4, and the bearings 8t) and 81 being received in a tubular member 95. The tube as is provided with a longitudinal slot 97 to accommodate the bearing plate 74, and the tube 96 is similarly provided with a slot 98 to accommodate the plate 76.

The slides 36 and 3d are caused to reciprocate in the clamp base assembly 34 by means of a pair of double acting hydraulic cylinders res and H32. The cylinder 199 is anchored to the clamp base assembly by any suitable means, and a piston illi associated therewith has a threaded outer end 165 (see FIGURE 3) which extends through a hole Ell-5 in the mounting lug 7b which is welded ton 134- to said lug. Accordingly, slide 36 is reciprocated toward and away from opposing slide 38 by conducting fluid under pressure to an appropriate end of double act- The cylinder 1% and a piston 1% associated therewith operate in similar fashion to reciprocate the slide 38, the piston res having a threaded end d portion 16% which extends through a hole 119 in the lug 7! and is anchored thereto by a nut 112. A front cover plate il iis utilized to enclose the various elements of the clamp base assembly 34.

The clamping arm 4% (shown best in FIGURES l and 4) comprises a pair of contoured side plates and 118, a front plate 124 and a back plate 122,, all of said plates being welded together toform a unitary arm assembly. FEGURE 1 illustrates the manner in which the clamping arm 4% is pivotally mounted on the slide 36. It will be noted that the support arms 64 and 66 on the slide extend into res ective clearances provided between the side plates 116 and 11 3 and the body portion of the clamping arm. A first hinge pin 125 extends through the hole 67 (see FIGURE 3) in the end of the support arm 64, and into both the side plate 116 and the body'portion of the arm 49. A similar hinge pin, indicated generally at 126, extends through the hole 63 in the support arm 66, and into both the side plate H8 and the body portion of the arm.

The clamp arm 49 is pivotable outwardly with respect to the opposed clamp arm 42 until the rear edge of the back plate, 122 bears against the torsion tube 44 in the areas where the support arms 64 and 66 are Welded thereto, after which further outward pivotal movement of arm do is prevented. The arm 49 is shown approximately in its outermost pivotal position in FIGURE 1. It is important to note that no springs are needed to control th pivotal position of the arm 43 since cam and cam fol lower means, to be described. below, are provided which continuously act to eltect this function.

A' roller is rotatably carried on the end of the side plate 116 by a pin E32, and a similar roller 334 is rotatably carried on the end of the opposite side plate 113. A fiat mounting plate 135 (shown best in FEGURE 3) comprises element of the clamp base assembly, and a pair of cam blocss 13 a and 138 are secured thereto by any suitable means. For example, screws as shown at 14% and shims as shown at I l-ll, may be utilized for this purpose. The earn 136 is positioned to cooperate with the roller 13% and the cam 13% is sim larly positioned to cooperate with the roller 134i, whereby the arm 46 is prevented from pivoting inwardly until the slide 36 carries it inwardly an amount sufiicient to permit the rollers 13% and 134 to roll oltth-e ends of the cam blocks 136 and 138, respectively.

A second pair or" sloping cams 7144 and are secured to the clamp base assembly for the purpose of engaging the rollers once they have passed over the ends of the cams 136 and 138, such engagement preventing further inward movement of the rollers and thus causing the arm l-l to pivot inwardly abouthinges 325 and 126 toward the opposing arm 42 as the slide 36 continues its inward rectilinear movement, Referring to FIGURE 1, the tubu lar member 94 has a lug 1% attached thereto, and the cam 144 is mounted on said lugmeans by screws 147 in a position to engage the roller 13% when the latter a base plate 15%, a front plate 158 and a back, plate 160,

all of which are welded or otherwise suitably secured. together to form a unitary arm assembly. Thearm 42 is rigidly secured to the slide 38 by means of a plurality of bolts to}; which extend through the arm base plate 156 and through. the slide base plate 72;rearwardly of which nuts 162 are applied, whereby the aim plate 1561's rigidly held in abutting relation against the plate 72. V

Clamppads 164 and 166 are hinged at the outer ends of the clamping arms by hinge pins 167 ;111:1168, repecdvely, andsuch padsserve as load gripping members and engage and hold a paper roll or the like when the clamping arms are moved together suficiently to permit a roll to be squeezed between the pads.

Each of the clamp pads may be provided with a pair of restraining rods or straps 170, with one end of each strap being hinged to a respective pad, and the other end slidably guided in tracks provided within the corresponding clamping arm. Such clamp pads are preferably biased to an outer position wherein the straps 170 are substantially retracted within the associated clamp arm, the pads being pivotable outwardly under load, but the latter pivotal movement being limited in accordance with the length of the strap members. A detailed description of clamp pad-s suitable for use with the present invention will be found in a copending application entitled Clamp Pad for Roll Clamping Mechanism, filed December 27, 1961, by Kenneth H. Mindrum, Serial No. 162,339, and assigned to the assignee of the present invention.

It will be understood that when the clamping arms 40 and 42 are extended as shown in FIGURES 1 and 2., the arm 40 is held in its outer pivotal position by the cam blocks 136 and 138 which act upon the rollers 138 and 134 carried by said arm. The arm 40 will be continuously held in the outermost pivotal position until the slide 36 on which it is carried is moved inwardly an amount suflicient to permit the rollers 13!) and 134 to roll off the ends of the cam blocks. If the slide 36 is then moved further inwardly, the rollers 130 and 134 will engage the sloping cams 144 and 145, causing the arm 40 to be pivoted inwardly as shown in FIGURE 4. When the slide 36 is again moved outwardly, the rollers will ride over the inner ends of the cams 136 and 138 so as to again bear against the sides thereof as shown in FIGURE 1, whereby the arm 40 will be returned to its outermost pivotal position. Accordingly, the pivotal position of the arm 40 is controlled at all times by the cam members, without need for any springs or other means to effect the desired positioning of said arm.

When the arms 40 and 42 are moved towards one another to clamp a paper roll or the like between the pivoted pad members 164 and 166, it will be seen that the clamping forces on the pad 164 are transmitted from the arm 40 to the hinge pins 125 and 126, which in turn load the support arm-s 64 and 66 and thereby apply torsional loads at the two ends of the torsion tube 44. Also, the force exerted by the piston 104 on the lug 70 is transmitted to the torsion tube. The foregoing loads are then transmitted from the tube 44 to the bearing plates 46 and 48, and finally to the four bearings 50, 52, 62 and 63 which are supported in the tubes 86 and 88 of the clamp base assembly 34.

It has been found that the torsion tube 44 provides an exceptionally strong and lightweight structure for transmitting clamping forces to the clamp base assembly 34, and that the bearings such as the bearing 50 are unusually simple to assemble to the bearing plates, and provide an effective expedient for slidably supporting the slide members 36 and 38.

It will be understood that various modifications and rearrangements may be made in the embodiments selected for disclosing our invention Without departing from the spirit and scope of the invention.

We claim:

1. In a clamping mechanism for lift trucks of the type having a pair of opposed clamping arms adapted to reciprocate inwardly towards and outwardly away from one another and having a main base portion with tubular members for guiding such movement, an arm carrier slide member, comprising: a slide base, a pair of spaced parallel bearing plates secured to said slidebase and extending therefrom toward said main base portion, and a pair of generally cylindrical bearings attached to each of said plates respectively, each of said bearings having a slot therein of a thickness approximately equal to the thickness of its respective bearing plate to facilitate seating of said bearings on said plates, one of each pair of bearings being rigidly mounted at the far inner end of a respective bearing plate, and the other of each pair of bearings being rigidly mounted adjacent the outer end of its respective plate, said bearings being adapted for reciprocation within said tubular members.

2. In a clamping mechanism for lift trucks of the type having a pair of opposed clamping arms adapted to reciprocate inwardly towards and outwardly away from one another and having a main base portion with tubular members for guiding such movement, an arm carrier slide member, comprising: a slide base, a pair of spaced parallel substantially flat bearing plates secured to said slide base and extending therefrom toward said main base portion, and a pair of bearings attached to each of said plates respectively, one of each pair of bearings being rigidly mounted at the far inner end of a respective bearing plate, and the other of each pair of bearings being rigidly mounted adjacent the outer end of its respective plate, each of said bearing being generally C-shaped and comprising a relatively thick disc having a fiat-sided slot therein of a thickness approximately equal to the thickness of its respective bearing plate to facilitate seating of said bearings on said plates, said bearings being adapted for reciprocation within said tubular members.

3. In a clamping mechanism for lift trucks of the type having a pair of opposed clamping arms adapted to reciprocate inwardly towards and outwardly away from one another and having a main base portion with tubular members for guiding such movement, an arm carrier slide member, comprising: a slide base, a pair of spaced parallel substantially flat bearing plates secured to said slide base and extending therefrom toward said main base portion, and four bearings each of which is generally C-shaped and comprises a relatively thick disc having a flat-sided slot therein of a thickness approximately equal to the thickness of said bearing plates, one pair of said bearings being mounted on the far inner ends of respective bearing plates with their slots disposed reanwardly, and a second pair of said bearings being mounted adjacent respective outer ends of said plates with their slots disposed forwardly, said bearings being adapted for reciprocation within said tubular members.

4. The invention of claim 3 wherein each of said four bearings is seated on a respective plate member and welded thereto, and each is enclosed by a corresponding substantially tubular bearing cover member.

References (Iited by the Examiner UNITED STATES PATENTS 2,874,862 2/59 Farmer et al 294-88 X 3,022,536 2/62 Floehr 26757 3,046,062 7/62 Wettstein 308-4 SAMUEL F. COLEMAN, Acting Primary Examiner.

LEO QUACKENBUSH, ANDRES H. NIELSEN, LOUIS I. DEMBO, Examiners. 

1. IN A CLAMPING MECHANISM FOR LIFT TRUCKS OF THE TYPE HAVING A PAIR OF OPPOSED CLAMPING ARMS ADAPTED TO RECIPROCATE INWARDLY TOWARDS AND OUTWARDLY AWAY FROM ONE ANOTHER AND HAVING A MAIN BASE PORTION WITH TUBULAR MEMBERS FOR GUIDING SUCH MOVEMENT, AN ARM CARRIER SLIDE MEMBER, COMPRISING: A SLIDE BASE, A PAIR OF SPACED PARALLEL BEARING PLATES SECURED TO SAID SLIDE BASE AND EXTENDING THEREFORM TOWARD SAID MAIN BASE PORTION, AND A PAIR OF GENERALLY CYLINDRICAL BEARINGS ATTACHED TO EACH OF SAID PLATES RESPECTIVELY, EACH OF SAID BEARINGS HAVING A SLOT THEREIN OF A THICKNESS APPROXIMATELY EQUAL TO THE THICKNESS OF ITS RESPECTIVE BEARING PLATE TO FACILITATE SEATING OF SAID BEARINGS ON SAID PLATES, ONE OF EACH PAIR OF BEARINGS BEING RIGIDLY MOUNTED AT THE FAR INNER END OF A RESPECTIVE BEARING PLATE, AND THE OTHER OF EACH PAIR OF BEARINGS BEING RIGIDLY MOUNTED ADJACENT THE OUTER END OF ITS RESPECTIVE PLATE, SAID BEARINGS BEING ADAPTED FOR RECIPROCATION WITHIN SAID TUBULAR MEMBERS. 